This invention relates to electrosurge generators having protective circuits at their output, and more specifically to an electrosurgical unit having a failsafe circuit at its output.
Electrosurge generators generally refer to systems which provide a high voltage output for application to various uses. The electrosurge generator is energized by a power supply in order to produce its high voltage output. Typical of such systems is an electrosurgical unit which includes an RF generator whose output is applied to a probe or blade, and is used during the course of surgical procedures.
In connection with electrosurgical units, it has been found that when the RF output is unmodulated, the output can be used for tissue cutting. On the other hand, by utilizing a pulse modulated RF voltage signal, coagulation of blood vessels can be achieved.
With such electrosurgical units, there is typically provided an oscillator having an output circuit which selectively produces the modulated or unmodulated output. The output circuit typically includes an output tank coil to which is connected an output device such as a probe, forceps or a blade.
During normal operation, the output voltage, whether modulated or unmodulated, is controlled by means of an intensity control knob to produce the desired voltage level. However, should there be a component failure or other failure within the electrosurgical unit, there exists the possibility of an extremely high voltage being applied at the output. Specifically, there is a potentially lethal internal DC power supply voltage which because of failures of certain components therein could appear at the patient contacting electrotip, and thus could cause severe traumatic effect, patient tissue damage, and in some instances, tragic results.
While there may exist in the prior art various components placed at the output of such electrosurgical units for protecting the patient, most of these components were designed to block the internal DC power supply voltage of the electrosurgical unit from the probe or other such device. As long as the particular protective components are operative, some protection could be afforded to the patient. However, should the components themselves fail, then the high internal voltage would be applied to the patient and the protective circuit itself is ineffective.